Tuen Mun Hospital said on Wednesday it is investigating a case involving a patient in intensive care who was connected to a ventilator that did not operate normally.

The 48-year-old suffered a cardiac arrest during the period, and his heartbeat was restored after two minutes of resuscitation. He remained in intensive care.

The hospital said the patient was first admitted in intensive care last Thursday with acute necrotising pancreatitis, complicated by acute kidney injury and respiratory failure. He was connected to a ventilator after a few days to help with his breathing.

On Tuesday morning, healthcare staff adjusted his ventilator and replaced the respiratory circuit. He developed oxygen desaturation four minutes later, triggering an alarm.

As staff attended to him, he had a cardiac arrest and clinical staff managed to resuscitate him two minutes later.

They also found out that the ventilator was not in normal operating mode, and workers quickly fixed the problem.

"The patient was conscious and able to respond to the instructions of the healthcare staff after the event," the hospital said in a statement, noting that a number of tests have been conducted so far and his vital signs were stable.

"The clinical team has initially determined that the incident had no significant impact on his overall condition." the statement added.

The hospital said it is very concerned about the case, and it has met with the patient's family to explain what happened.

It said it has reported the case to the head office of the Hospital Authority, and it will make recommendations after its probe to prevent similar incidents from happening.